Operation experiences of radioactivity monitoring system for the mercury system in J-PARC

Harada, Masahide; Tajima, Takahiro*; Ito, Taku*; Masuda, Shiho; Kinoshita, Hidetaka; Sakai, Kenji; Muto, Giichi*; Suzuki, Akio*; Haga, Katsuhiro

JPS Conference Proceedings (Internet), 45, p.011053_1 - 011053_5, 2026/06

https://doi.org/10.7566/JPSCP.45.011053

At Materials and Life science experimental Facility (MLF) in J-PARC, a mercury target of an intense pulsed spallation neutron source is designed to be irradiated by 3 GeV and 1MW proton beams to provide high intensity neutron beams to a suit of neutron instruments. A unified mercury radioactivity monitor (UHAM) is installed to find an indication of failure of the mercury target and loop system by detecting radioactive materials leaked from the system with a gamma-ray energy analysis with Germanium semi-conductor detectors. It is composed of three units of sampling port and radiation monitors: 1) HAM for interstitial helium gas layer between the mercury vessel and surrounding water shroud of the mercury target, 2) CAM for atmosphere in the hot cell where the target loop is operated and 3) VAM for helium gas in the helium vessel where the target vessel is installed. Once any leakages of radioactive materials are detected, an alarm signal is issued immediately to the accelerator control system to stop beam operation. Software and hardware have been upgraded yearly. For example, two Ge detectors are used for HAM for redundancy, NaI Scintillation detectors are also used as supplemental for the Ge detector to keep availability of the system for high counting rate event. In addition, A gas monitor is equipped at CAM to detect tritium. Until now, several operation experiences could be obtained as the follwoing. 1) Xe-121 and Xe-123 gas could be detected at CAM. These radio-active gaseous radioactive nuclides are slightly leaked from cover gas of mercury target. 2) Humidity in the helium vessel could be detected at VAM, because detection of annihilation gamma-ray and N-15 were increased. 3) The detection of Ar-41 indicated the air mixing in helium atmosphere.

Maintenance of used components in spallation neutron source; Moderator reflector and proton beam window

Teshigawara, Makoto; Kinoshita, Hidetaka; Wakui, Takashi; Meigo, Shinichiro; Seki, Masakazu; Harada, Masahide; Ito, Manabu; Suzuki, Toru; Ikezaki, Kiyomi; Maekawa, Fujio; et al.

JAEA-Technology 2012-024, 303 Pages, 2012/07

JAEA-Technology-2012-024.pdf:46.04MB

3 GeV Protons with 1 MW beam power are irradiated to mercury target of spallation neutron source in Materials and Life science Facility (MLF), which is one of facilities of J-PARC. Irradiated components, such as target container, moderator, reflector and proton beam window, are needed to replace periodically due to irradiation damage of high energy protons and neutrons. These used components are replaced remotely because of highly activated. Maintenance scenario was settled so as to handle these components. Required remote handling machines were designed and installed in hot cell and other room of the MLF. We performed remote handling tests by using actual components to confirm the design. We report results, such as replacement procedure, trouble and its solution, etc., for moderator, reflector and proton beam window in order to provide the handling of actual used components.

27th report of ITPA topical group meeting

Osakabe, Masaki*; Shinohara, Koji; Toi, Kazuo*; Todo, Yasushi*; Hamamatsu, Kiyotaka; Murakami, Sadayoshi*; Yamamoto, Satoshi*; Idomura, Yasuhiro; Sakamoto, Yoshiteru; Tanaka, Kenji*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(12), p.839 - 842, 2009/12

http://ci.nii.ac.jp/naid/40016957892

no abstracts in English

Energetic protons from a few-micron metallic foil evaporated by an intense laser pulse

Matsukado, Koji*; Esirkepov, T. Z.; Kinoshita, Kenichi*; Daido, Hiroyuki; Utsumi, Takayuki*; Li, Z.*; Fukumi, Atsushi*; Hayashi, Yukio; Orimo, Satoshi; Nishiuchi, Mamiko; et al.

Physical Review Letters, 91(21), p.215001_1 - 215001_4, 2003/11

https://doi.org/10.1103/PhysRevLett.91.215001

no abstracts in English

Radiation monitoring on replacement work of the mercury target vessel in J-PARC

Masuyama, Koichi; Sato, Koichi; Yoshino, Koji; Tajima, Takahiro*; Seki, Kazunari; Kasugai, Yoshimi; Miyamoto, Yukihiro

no journal, , 

The mercury target vessel used in the Materials and Life Science Experimental Facility (MLF) in the Japan Accelerator Research Complex (J-PARC) needs to be replaced periodically. The replacement work, which is conducted in the hot cell, associates with release of radioactive materials produced via spallation reactions between protons and mercury. Therefore we monitored radioactivity of dust and air samples in the hot cell. By the monitoring, we newly found peculiar phenomena on the behavior of radioactive products, which is important for radiation control. In this work, we will show the monitoring data and the new observation.

Development of sample radio-activity evaluation code at Materials and Life Science Facility in J-PARC

Harada, Masahide; Yamaguchi, Yuji; Hashimoto, Norimichi*; Ito, Taku*; Tajima, Takahiro*; Oku, Takayuki; Haga, Katsuhiro; Ikeda, Hiroshi*; Tamura, Satoshi*

no journal, , 

In Materials and Life Science Experimental Facility at J-PARC, carbon and mercury targets bombarded by 3 GeV and 1 MW proton beam produce muons and neutrons to provide to muon and neutron instruments. As the samples irradiated by muons and neutrons produce radioactive materials, an estimation of the radioactive materials produced in the irradiated samples is necessary for the stable operation and management of the facility. Therefore, a sample radio-activity evaluation code was developed using data from the DCHAIN-SP-2001 code. By selecting the irradiation conditions for each experiment and entering the information for each sample, the radio-activity of a sample can be calculated by multiplying the neutron flux by the activation cross section. The code is a servlet application, programed by JAVA, accessible on the Web, and can be used from the internal network. In the future, we will conduct activation experiments on various materials and validate this code.